The loading of filter media for multi-media filters should be in strict layer sequenceand operation specifications to ensure the effectiveness of filtration and stableequipment operation.
Preparation Prior to Loading
• Verify particle size range, depth of fill and layering sequence for each filter medialayer. The order is usually increasing particle size and decreasing density, e.g.anthracite - quartz sand - pebbles.
• Prepare measuring instruments, level and levelling instruments to check theheight error of each layer < 50 mm.
• Clean out inside of the filter and check that water collector is properly installed toprevent media leakage into collection system.
• If the filter interior has protrusions or steps, draw control lines for the height ofeach media layer.
Loading Steps in Tiers
1.Loading of Support Layer(Pebbles)
• Layer by size, from largest to smallest, each layer height 50-100 mm.
• Fill each layer and level and lightly compact to produce a flat surface.
2. Filter Layer (Quartz Sand etc.) Loading...
• Load in layers according to the particle size gradient from bottom to top.
• Leveleach layer immediately after loading.
• At the interface of adjacent layers of similar particle sizes a permeable isolationmesh can be inserted to prevent mixing during backwashing.
3.Upper Layer ( Anthracite etc.) Loading...
• Spread the media slowly and evenly to prevent dumping too quickly in one placewhich can disturb the underlying layers.
• Use a level to check surface flatness after reaching the design height. Do not shakevigorously for small adjustments.
Warnings
• The particle size ratio between successive layers should be > 2 to prevent the finemedia from seeping into the lower layer.
• Once media loading is completed, begin filtration at normal flow within 30 minutesand continue for 30 minutes before the first backwash. Search for any media
mixing.
• Check media for compaction, loss or ageing on a regular basis and repair orreplace as needed.
By following these steps, we can have a clear layering, a stable interface and anefficient operation of the multi-media filter.
